oachalon, since you have a powered sub, assuming your RX-V1400 is properly configured (LFE=SWFR, crossover=80hz, all speakers=small), your receiver is probably using only about 1 watt/channel to achieve extremely loud levels.

Reason is most of amp power goes to bass frequencies, and you've already off loaded that. Since you're probably only using 1/80th the capability of your amp, increasing your headroom from 80x to 200x is unlikely to make an audible difference.

I'd suggest you get an SACD/DVD-A player and some discrete surround discs. You will really enjoy those. You already have the surround receiver and speakers.

Whether changing amps makes an audible difference is debatable. Whether the multichannel SACD version of Pink Floyd's Dark Side of the Moon is audibly different (most would say better) than the stereo version is not debatable. Anyone with ears can hear the difference.

Go to http://store.acousticsounds.com/, query on SACD and DVD-A, and see if your favorite artists have any discs out.